A formal nethod (a networked formal method)

A year-long trial has seen a large lightweight verification problem treated by an ad hoc distributed network of identical solvers. The trialled problem is the semantic analysis of the C code in the Linux kernel to exclude a common deadlock possibility. The aim of the programme behind the experiment is to develop a viable loosely coupled distributed formal method which a community of interested part-time helpers on the net can lend their computing cycles to as they will, or send their own verification problems to for solving.     

On stability of a formal concept

In this paper we define and analyze stability of a formal concept. A stability index is based on the idea of a dependency in a dataset that can be reconstructed from different parts of the dataset. This idea, underlying various methods of estimating scientific hypotheses, is used here for estimating concept-based hypotheses. Combinatorial properties of stability indices, algorithmic comlpexity of their computation, as well as their dynamics with arrival of new examples are studied. This work was supported by the project COMO (Concepts and Models) of the Deutsche Forschungsgemeinschaft (DFG) and Russian Foundation for Basic Research (RFBR).     

On a formal semantics of tabular expressions

Parnas et al. (Janicki et al., in: Brink, Kahl, Schmidt (Eds.), Relational Methods in Computer Science, Springer, Berlin, 1997; Parnas, Commun. ACM 26 (8) (1983) 572–581; Parnas and Madey, Sci. Comput. Programm. 25 (1) (1995) 41–61; Parnas et al., IEEE Trans. Software Eng. 20 (12) (1994) 948–976) advocate the use of relational model for documenting the intended behaviour of programs. In this method, tabular expressions (or tables) are used to improve readability so that formal documentation can replace conventional documentation. Parnas (CRL Report 260, Telecommunications Research Institute of Ontario (TRIO), Mcmaster University, Hamilton, Ontario, Canada, 1992) describes several classes of tables and provides their formal syntax and semantics. In this paper, an alternative, more general and more homogeneous semantics is proposed. The model covers all known types of tables used in Software Engineering.     

On a formal definition and application of dimensional design

Dimensional design (DD) is a simple, practical and systematic layout technique for the display of programs, specifications, expressions, etc. for application in the general area of software. Formalizations of DD are introduced, the main one being algebraic, and the usage of DD in real software projects is outlined; one of them corresponds to a software system for the telecontrol centre of a power network. The formal definitions of DD which are presented arise during the design of a syntax-driven editor generator for languages whose ‘phrases’ are DDs. Grammars for the definition of such languages are introduced in the paper. The varied usage of DD within the generator design is examined: grammatical, functional and algebraic notations in particular are considered. The samples of these DD representations that are given illustrate the enhancement of readability achieved, and illustrate the suitability of DD for use in the specification area in general.     

一种云存储环境下保障数据机密性的方法

为保证用户数据的机密性,业界普遍将数据加密后存储在云端。提出了一种云存储系统中保障数据机密性的方法,其特点有:(1)加解密系统部署于云存储服务器的前端,在客户端和云存储服务器之间对用户数据进行加解密;(2)对用户数据的加解密是实时进行的,在数据上传的传输过程中进行加密,在数据下载的传输过程中进行解密;(3)加解密系统对用户端和云服务器端是透明的。当前广泛使用的基于HTTP协议传输的云存储系统如Amazon S3、OpenStack Swift等可以直接使用该方法。测试结果表明:本方法在不降低数据传输吞吐率的基础上,能有效卸载云存储系统的数据加解密负担。     

不完备形式背景中的知识获取方法

重点讨论了不完备形式背景中的相容概念以及基于相容概念的相容规则获取方法,同时给出了相应的构造算法。为了压缩规模庞大的相容规则集合,提出了一条推理规则来减少生成冗余相容规则的数目,最终得到一个完备的无冗余的相容规则集合。通过参数的设定可以满足不同用户的实际需求,实例证明该方法是有效的。该方法不仅为不完备形式背景的处理提供了一条新的途径,同时也为更深入的研究奠定了基础。     

Integrating a formal method into a software engineering process with UML and Java

We describe how CSP-OZ, a formal method combining the process algebra CSP with the specification language Object-Z, can be integrated into an object-oriented software engineering process employing the UML as a modelling and Java as an implementation language. The benefit of this integration lies in the rigour of the formal method, which improves the precision of the constructed models and opens up the possibility of (1) verifying properties of models in the early design phases, and (2) checking adherence of implementations to models. The envisaged application area of our approach is the design of distributed reactive systems. To this end, we propose a specific UML profile for reactive systems. The profile contains facilities for modelling components, their interfaces and interconnections via synchronous/broadcast communication, and the overall architecture of a system. The integration with the formal method proceeds by generating a significant part of the CSP-OZ specification from the initially developed UML model. The formal specification is on the one hand the starting point for verifying properties of the model, for instance by using the FDR model checker. On the other hand, it is the basis for generating contracts for the final implementation. Contracts are written in the Java Modeling Language (JML) complemented by CSP_jassda, an assertion language for specifying orderings between method invocations. A set of tools for runtime checking can be used to supervise the adherence of the final Java implementation to the generated contracts. This research was partially supported by the DFG project ForMooS (grants OL 98/3-2 and WE 2290/5-1). C. B. Jones     

A decomposition of a formal specification: an improvedconstraint-oriented method

In this paper, the authors propose a decomposition method for a formal specification that divides the specification into two subspecifications composed by a parallel operator. To make these specification behaviors equivalent before and after decomposition, the method automatically synthesizes an additional control specification, which contains the synchronization information of the decomposed subspecifications. The authors prove that a parallel composition of the decomposed subspecifications synchronized with the control specification is strongly equivalent with the original (monolithic) specification. The authors also write formal specifications of the OSI application layer's association-control service and decompose it using their method as an example of decomposition of a practical specification. Their decomposition method can be applied to top-down system development based on stepwise refinement     

rCOS: a formal model-driven engineering method for component-based software

Model-driven architecture (MDA) has become a main stream technology for software-intensive system design. The main engineering principle behind it is that the inherent complexity of software development can only be mastered by building, analyzing and manipulating system models. MDA also deals with system complexity by providing component-based design techniques, allowing independent component design, implementation and deployment, and then system integration and reconfiguration based on component interfaces. The model of a system in any stage is an integration of models of different viewpoints. Therefore, for a model-driven method to be applied effectively, it must provide a body of techniques and an integrated suite of tools for model construction, validation, and transformation. This requires a number of modeling notations for the specification of different concerns and viewpoints of the system. These notations should have formally defined syntaxes and a unified theory of semantics. The underlying theory of the method is needed to underpin the development of tools and correct use of tools in software development, as well as to formally verify and reason about properties of systems in mission-critical applications. The modeling notations, techniques, and tools must be designed so that they can be used seamlessly in supporting development activities and documentation of artifacts in software design processes. This article presents such a method, called the rCOS, focusing on the models of a system at different stages in a software development process, their semantic integration, and how they are constructed, analyzed, transformed, validated, and verified.     

一种基于随机二态编码的交易保密验证方法

针对密文状态下的交易金额验证问题,采用安全多方计算原理提出一种新的随机二态编码方法。应用这种编码方法和随机产生的全序集合对交易进行编码,构造一个能使交易完全一一对应的编码向量。基于此,将交易保密验证问题转换为保密计算编码向量中部分元素累加问题。通过累加结果区分交易关系,结合椭圆曲线及同态特性进而解决交易保密验证问题。最后在半诚实模型下利用模拟范例证明了方法的正确性和安全性。理论分析表明,与已有方案相比,所提出的方法具有密钥短小、实用性强等优点。     

一种融合多级特征信息的图像语义分割方法

卷积神经网络因为其强大的学习能力,已经在语义分割任务中取得了显著的效果,但是如何有效地利用网络在浅层次的视觉特征和深层次的语义特征一直是研究的热点,以此为出发点,提出了一种融合多级特征信息的图像语义分割方法。通过空洞卷积提取各层级的特征,并不断迭代深层特征来丰富低级视觉信息,最后与高级语义特征合并融合,得到精细的语义分割结果。实验在PASCAL VOC 2012数据集上与主流的五种方法进行了比较,在GTX1080Ti的环境下该方法与其中性能第二的模型mIoU（mean intersection-over-union）值相比提高了2.1%,与其中性能第一的模型mIoU值仅相差0.4%,表明该方法能有效利用多层级的特征信息,实现了图像语义分割的目的。     

On integrating event definition and event detection

We develop, in this paper, a representation of time and events that supports a range of reasoning tasks such as monitoring and detection of event patterns which may facilitate the explanation of root cause(s) of faults. We shall compare two approaches to event definition: the active database approach in which events are defined in terms of the conditions for their detection at an instant, and the knowledge representation approach in which events are defined in terms of the conditions for their occurrence over an interval. We shall show the shortcomings of the former definition and employ a three-valued temporal first order nonmonotonic logic, extended with events, in order to integrate both definitions.     

On a new formal proof model for RFID location privacy

We discuss a recently proposed formal proof model for RFID location privacy. We show that protocols which intuitively and in several other models are considered not to be location private, are provably location private in this model. Conversely, we also show that protocols which obviously are location private, are not considered location private in this model.Specifically, we prove a protocol in which every tag transmits the same constant message to not be location private in the proposed model. Then we prove a protocol in which a tag's identity is transmitted in clear text to be weakly location private in the model.     

Steps towards a method for the formal modeling of dynamic objects

Fragments of a method to formally specify object-oriented models of a universe of discourse are presented. The task of finding such models is divided into three subtasks, object classification, event specification, and the specification of the life cycle of an object. Each of these subtasks is further subdivided, and for each of the subtasks heuristics are given that can aid the analyst in deciding how to represent a particular aspect of the real world. The main sources of inspiration are Jackson System Development, algebraic specification of data- and object types, and algebraic specification of processes.     

An operational formal definition of PROLOG: a specification method and its application

We present in this paper a logic programming specification language and its application to the formal specification of PROLOG dialects (Marseille-Edinburgh like dialect or parallel logic programs). In particular it is used in the standardization work of PROLOG. The specification language is based on normal clauses (definite clauses with possibly negative literals in the body) whose semantics is the set of the (generalized) proof-trees. We restrict the specification language to stratified programs and ground proof-trees such that its semantics fits with most of the usual known semantics in logic programming. The specification language is fully declarative in the sense that it is written in a pure logical stule. It is relatively easy to deduce an executable specification from a specification written in such a language. Part of the specification are the associated comments and a methodology has been developed to write these. Without the comments a formal specification cannot be understood; they are partly formal and serve only to help to understand the axioms. They are a natural language form of formal statements relative to the correctness and the completeness of the axioms with regards to some intended meaning. We show in this paper how this specification language can be used to specify dialects of PROLOG. The presented example is just a sample of PROLOG but fully developed here. The specification language has already been used for real dialects as PARLOG and standard PROLOG. This specification method is also interesting because it illustrates the power of logic programming to make specifications. It seems to us that logic programming is generally considered as “impure” executable specification. Our purpose is to show that logic programming may also be used as a perhaps low level but full specification language.     

On transformations of formal power series

Formal power series are an extension of formal languages. Recognizable formal power series can be captured by the so-called weighted finite automata, generalizing finite state machines. In this paper, motivated by codings of formal languages, we introduce and investigate two types of transformations for formal power series. We characterize when these transformations preserve recognizability, generalizing the recent results of Zhang [16] to the formal power series setting. We show, for example, that the “square-root” operation, while preserving regularity for formal languages, preserves recognizability for formal power series when the underlying semiring is commutative or locally finite, but not in general.     

On the complexity of formal grammars

Summary The time and space complexity of the class of languages generated in linear time by context-sensitive grammars is investigated. Among other results it is shown that the membership question for languages in the class is NP-complete.This research was supported in part by the National Science Foundation under Grants DCR75-15945 and MCS77-11360     

A method for integrating ergonomics analysis into maintainability design in a virtual environment

Designers must consider human factors/ergonomics when making decisions from the perspective of maintainability. As an important aspect of maintainability, maintenance space should be made adequate at the design stage to achieve a convenient maintenance process. A maintenance space evaluation method that considers ergonomics is proposed in this study. By comparing free swept volumes and constrained swept volumes in a virtual environment, maintenance space could be evaluated quantitatively and objectively. The results of the evaluation are obtained by combining the principles of ergonomics and maintainability. These results can help designers improve product design such that it fits ergonomics and maintainability requirements. A case study is introduced at the end of this paper to demonstrate the feasibility of the proposed method in efficiently evaluating the maintenance space based on the layout design of the product components in the design stage.Relevant to industryFor a large number of disasters caused by human errors in current industry, the result of this study contributes a guide to fully consider human factors in maintainability design through virtual environment and is beneficial to designers and engineers of industrial application fields.     

On stability of formal fuzziness systems

The structure of formal fuzziness systems as some abstraction on real fuzziness systems is debated. Then the global definition of α-stability is given. First some necessary and sufficient conditions for α-stability are given for the case of R = A ? B (Sec. 2) and later for the case of R defined by an implication chain of any finite length (Sec. 4). In Secs. 5 and 6 notions of α-stability and α-β strong decision stability are introduced, and some theorems on necessary or sufficient (or both) conditions for these kinds of stability, imposed on the structure of an implication chain, are proved. In Sec. 3 the good-mapping property of a fuzzy relation matrix is analyzed, and because of its heuristic importance it is assumed in further sections. In many cases examples are given to illustrate definitions and theorems or conclusions.